The invention relates to slippers in general, and more particularly relates to the disposable slippers which may be used especially by the people who enjoy travels in a long-distance train or a sight-seeing bus, and by the inpatients as well as the outpatients of a hospital. The slippers are well designed to be comfortable to wear preventing the heels of feet from being soiled on the floorboards. Moreover the slippers may be produced at an extremely low cost and may be easily reclaimed to new products.
So far many slippers have been proposed for the purposes as mentioned above. These slippers, however, have been insufficient to comply with the requirements such as to be comfortable to wear, to prevent the socks from getting dirty on the floorboards, to be produced at a low cost with an efficient productivity, to be easily disposed after the slippers have been used, and so on. It will be proper to explain the prior by way of an example in FIGS. 1 and 2 showing one of the older slippers which is now actually reduced to practice. The slipper 1 has a sole 2 made so narrow as is designed in match with the soles of foot in general, and especially the heel part 2a is particularly narrow. The sole 2 is made of a cardboard which is covered with upper and lower sheets 4 of synthetic resin which are welded to each other by heat-treatment along the edge 4a of the sole. The slipper 1 has an instep 5, which is made of the same material with that of the cover sheets 4, welded by heat-treatment on both sides 5b thereof to the cover sheets 4 at the edge of the slipper. The instep 5 is folded at the intermediate parts 5a thereof to maintain the slipper flat when the latter is unused, such that the instep may be unfolded when the slipper 1 is used.
According to the prior art as mentioned above, since the heel part 2a is so small and narrow, the heel of foot is liable to protrude out of the heel part 2a of the slipper 1 when the user walks around in the places as mentioned above and when the user makes himself at home including his or her legs in the outward directions, for example, in the long-distance train. As the result, the socks are partly pressed against the floorboard and get dirty. It is well known that the travellers in general even in their seats in the long-distance train will relax themselves inclining their legs more or less in the outward directions, instead of strictly posing in their seats. It is therefore a fatal defect for those who have neat habits that the heel part of slipper is small and narrow.
On the other hand, from the viewpoint of manufacture, the sole 2a of the conventional slipper 1 is designed irrespectively of the fitness in a sense of economically cutting out the form from a material such as the cardboard. It is therefore unavoidable that there will be left much amount of useless part of the cardboard after the forms have been cut out. Further since it is required that the instep 5 of the slipper 1 is folded at the intermediate parts 5a thereof with predetermined angles and predetermined dimensions, such additional manufacturing process and equipment therefor will be needed. Further since the cover sheets 4 is required to be welded by heat-treatment to each other along the edge 4a of the sole 2 and also the instep 5 is required to be welded by the same manner on both sides 5b thereof to the sheets 4, so many additional manufacturing processes and heat equipment will be needed. As the result, the manufacture cost becomes rather high.
Further from the viewpoint of the disposal after the slippers have been used, since the cover sheets 4 and the instep 5 are made of synthetic resin of a considerable thickness and of considerable dimensions and these may not be recycled, it becomes very difficult to dispose of the used slippers if they are released in a great quantity, for example, by the National Railways Corporation and other railway companies which deal with such slippers. These used slippers will produce a poisonous gas to cause a public hazard in case these are disposed of by way of combustion. In any events, the conventional slipper 1 is very uneconomical in view of the fact that this can not be recycled and fails to contribute to the purpose of material-saving.